JP4191400B2 - Image display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image display device, and more specifically, an image display device using a liquid crystal display device, wherein the brightness of a backlight of the liquid crystal display device is adjusted according to the brightness of ambient light (ambient light). The present invention relates to an image display device that makes it easy to see a display image.
[0002]
[Prior art]
In the medical field, various diagnostic image acquisition devices using X-rays have been used, and X-ray imaging devices, CR (Computed Radiography) devices, CT (Computed). -Tomography) devices, MRI (magnetic resonance imaging) devices, etc. have come into practical use.
[0003]
Medical image information acquired by these devices is recorded on photographic film and observed on a shaw casten or recorded on another recording medium, and then subjected to desired image processing such as frequency processing and gradation processing. After being displayed, it is displayed on an image display device (monitor screen) and observed to be used for diagnosis in a medical field.
[0004]
Conventionally, a CRT display device has been used as the image display device described above, but recently, a so-called flat panel display using a liquid crystal panel, an organic EL panel, or the like is about to be used. This flat panel display generally has advantages such as space saving, light weight, and low power consumption as compared with a CRT display device, and is expected to become more popular in the future.
[0005]
In addition, with CR (Computed Radiography) device, a part of radiation energy is accumulated by irradiation of radiation, and then accumulated by irradiating excitation light such as visible light and infrared light. The radiation image information of a subject such as a human body is recorded on a storage phosphor (stimulable phosphor) that exhibits stimulable light emission in accordance with the emitted radiation energy. By detecting it, photoelectrically reading it to obtain an image signal, processing the obtained image signal, outputting a soft copy image to an image display device, or outputting a hard copy image to an X-ray photographic film Radiation image recording / reading apparatus.
[0006]
A CT (Computed Tomography) apparatus uses computed tomography, and obtains projection images of parallel beams on a straight line by X-rays at various angles. An X-ray absorption rate, that is, a tissue configuration by an internal tissue is obtained and output as a soft copy image or a hard copy image. As a reconstruction method from a projection image, there are methods such as a successive approximation method and a back projection method.
[0007]
An MRI (magnetic resonance imaging) apparatus is an apparatus that extracts and images an electromagnetic wave signal that is normally generated by the nuclear magnetic resonance effect of hydrogen atoms. Specifically, when an electromagnetic wave having a natural resonance frequency of the nucleus is applied from the outside to bring the nuclear magnetic moment derived from the spin into an excited state, and the above-described electromagnetic wave is stopped from this state, the excited nucleus is in the ground state. In this process, an electromagnetic wave having a resonance frequency is emitted, and this is received by a coil, imaged, and output as a soft copy image or a hard copy image.
[0008]
[Problems to be solved by the invention]
By the way, in the display device using the above-mentioned liquid crystal panel, even if the liquid crystal is completely turned off, some light leaks (so-called leaked light). There is a problem that changes.
[0009]
This problem is irrelevant when viewed in a bright place, but is very difficult to see when it is somewhat dark. Specifically, in a slightly dark observation environment, light from the liquid crystal panel leaks, resulting in an image with reduced contrast.
[0010]
In contrast, in principle, when the ambient light is bright, the backlight of the liquid crystal is brightened, thereby making the low-density area bright and easy to see, and conversely, when the ambient light is dark, the backlight of the liquid crystal is turned on. However, when the backlight is darkened as described above, it is necessary to consider leakage light determined by the extinction ratio of the liquid crystal.
[0011]
The present invention has been made in view of the above circumstances, and an object of the present invention is to solve the problems in the prior art, and in an image display device using a liquid crystal display device, the brightness of ambient light (ambient light). It is an object of the present invention to provide an image display device that makes it possible to make a displayed image truly easy to see.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, an image display device according to the present invention is an image display device using a liquid crystal display device including a liquid crystal display panel and a backlight, and when the ambient light is bright , the back of the liquid crystal display device. brighter light, when ambient light is dark, the backlight, and have a brightness adjustment unit of the backlight light leakage of a liquid crystal display which is determined by the liquid crystal of the extinction ratio is dark so as not to more than a predetermined, the back The light brightness adjustment means includes first detection means for detecting the brightness of the backlight, and first brightness estimation means for estimating the brightness a of the leaked light based on an output signal from the first detection means. And a second detector for detecting the brightness of the ambient light, and the brightness of the ambient light determined in advance based on the output signal from the second detector and the response of the liquid crystal screen corresponding thereto. The brightness b of the backlight based on the output from the second brightness estimator for estimating the brightness b based on the relationship between the brightness b and the first brightness estimator and the second brightness estimator. And a backlight brightness adjustment signal generating means for controlling the brightness, and the brightness of the backlight is controlled so that the brightness a is not more than twice the brightness b. To do.
[0013]
Here, the backlight brightness adjusting means uses the backlight obtained in advance based on a relationship between a predetermined luminance value of the backlight and leakage light determined by the extinction ratio of the liquid crystal. Means for estimating the luminance a of the leakage light of the liquid crystal screen from the brightness of the current backlight estimated based on the relationship between the time and the light emission luminance and the relationship between the backlight control signal and the light emission luminance; From the brightness of the ambient light detected by the means for detecting the brightness of the ambient light based on the relationship between the brightness of the ambient light and the brightness b by reflection of the liquid crystal screen corresponding to the ambient light, and means for determining the brightness b by reflection of the liquid crystal screen corresponding to the brightness of that, the brightness of the backlight, the brightness a is one that is controlled to be below 2 times the brightness b Preferred.
[0016]
Further, the means for controlling the brightness of the backlight is such that the brightness of the backlight is 70% or more of the maximum brightness of the backlight in a range where the brightness a is less than twice the brightness b. It is preferable to control it.
More preferably, the means for controlling the brightness of the backlight is controlled so that the luminance a is equal to or lower than the luminance b.
The means for controlling the brightness of the backlight controls the brightness of the backlight to be 70% or more of the maximum brightness of the backlight in a range where the brightness a is less than or equal to the brightness b. Is preferred.
[0017]
In this specification, ambient light is light existing in the environment where the image display device according to the present invention is installed, and more specifically, ambient light in the environment (this is also referred to as ambient ambient light). ).
Bright is a state with a lot of light in the environment as described above, and dark is an opposite state. Further, the brightness of the backlight is used synonymously with the brightness of the backlight, and is not directly related to the brightness of the environment.
Further, the extinction ratio is a ratio of light that leaks when the backlight is on and the liquid crystal is completely off , and is expressed as a ratio between when the backlight is completely on and when it is completely off.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0019]
FIG. 1 is a block diagram illustrating a schematic configuration of an image display device 30 according to an embodiment of the present invention. FIG. 2 illustrates a schematic configuration of a control system including a controller 36 of the image display device 30 according to the present embodiment. FIG.
1 and 2, reference numeral 10 denotes a liquid crystal display panel unit that is a main part of the image display device 30 according to the present embodiment, 12 denotes a liquid crystal display panel of the liquid crystal display panel unit 10, and 20 denotes a back of the liquid crystal display panel unit 10. 32, a backlight monitor provided in a part of the backlight 20, 34 an external light monitor for detecting external light in the environment where the image display device 30 is installed, and 36 a backlight monitor 32 and an external light monitor. A controller 38 generates a backlight adjustment signal for determining whether to adjust the brightness of the backlight based on the monitor signal from the light monitor 34, and 38 outputs the output of the backlight 20 based on the backlight adjustment signal from the controller 36. 1 shows a backlight control device to be controlled.
[0020]
In the controller 36 shown in FIG. 2, reference numeral 40 denotes external light that estimates the luminance b due to reflection of external light on the liquid crystal screen of the liquid crystal display panel unit 10 based on external light (environment light) detected by the external light monitor 34. A reflection luminance estimation unit 44 is a leakage light luminance estimation unit 42 that estimates the luminance (minimum luminance) a of the leakage light of the liquid crystal screen based on the brightness (monitor value) of the backlight 20 detected by the backlight monitor 32. Is a backlight adjustment signal generation unit that generates a backlight adjustment signal from the luminance a and the luminance b obtained by the leakage light luminance estimation unit 44 and the external light reflection luminance estimation unit 40. Reference numerals 41 and 45 denote external light reflections, respectively. A memory connected to the luminance estimation unit 40 and the leaked light luminance estimation unit 44.
[0021]
FIG. 3 is an operation flowchart for explaining the operation corresponding to the brightness of the ambient light in the control system of the image display device 30 including the controller 36 and the backlight control device 38. Hereinafter, the configuration of the control system of the image display device 30 according to the present embodiment and the operation corresponding to the brightness of the ambient light in the image display device 30 will be described with reference to FIGS.
[0022]
The external light monitor 34 detects the brightness of the external light (step 51 in FIG. 3). The brightness (monitor value) of the external light detected by the external light monitor 34 is sent to the external light reflection luminance estimation unit 40 of the controller 36.
In step 52, the external light reflection luminance estimation unit 40 reads the relational expressions, tables, and the like that are obtained in advance from the memory 41, and uses them to determine the brightness of the external light transmitted from the external light monitor 34 ( From the monitor value), the luminance b due to reflection of external light on the liquid crystal screen, that is, the luminance b due to reflection of the liquid crystal screen corresponding to the ambient light state (brightness) detected by the external light monitor 34 is estimated. The relational expression and table between the external light monitor value and the luminance value b used here are the external light monitor value detected from the external light monitor 34 and the external light reflection (backlight) of the liquid crystal screen at the time of the external light. It is preferable to calculate from the relationship with the luminance b by 20).
The luminance value b estimated by the external light reflection luminance estimation unit 40 is sent to the backlight adjustment signal generation unit 42.
[0023]
On the other hand, the backlight monitor 32 detects the brightness of the backlight of the liquid crystal panel unit 10 (step 53 in FIG. 3). The brightness (monitor value) of the backlight 20 detected by the backlight monitor 32 is sent to the leakage light luminance estimation unit 44 of the controller 36.
In step 54, the leaked light luminance estimation unit 44 reads a predetermined relational expression, table, and the like from the memory 45, and uses this to calculate the backlight sent from the backlight monitor (luminance monitor) 32. From the brightness (monitor value), the luminance a of the leakage light of the liquid crystal screen, that is, the luminance value of the leakage light of the liquid crystal screen determined by the extinction ratio of the liquid crystal is estimated from the luminance value of the backlight. The relational expression and table between the backlight monitor value and the luminance value a used here are the backlight monitor value detected in advance from the backlight monitor 32, and the minimum luminance value (leakage light) of the liquid crystal determined by the extinction ratio. It is preferable to calculate from this relationship.
The luminance value a estimated by the leakage light luminance estimation unit 44 is sent to the backlight adjustment signal generation unit 42.
[0024]
Next, in step 55, the backlight adjustment signal generation unit 42 compares the luminance a and the luminance b sent from the leakage light luminance estimation unit 44 and the external light reflection luminance estimation unit 40, respectively. That is, it is checked whether or not a ≦ n · b (n is appropriately set within the range of 2 to 1).
[0025]
If it is determined in the check in step 55 that a ≦ n · b is established, it is not necessary to adjust the brightness of the backlight 20, and the backlight 20 can be maintained as it is (set state). Good. Therefore, the backlight adjustment signal generation unit 42 does not generate a backlight adjustment signal for adjusting the brightness adjustment of the backlight 20 and does not send it to the backlight control device 38. For this reason, the brightness of the backlight 20 is maintained in the set state by the backlight control device 38.
On the other hand, if it is determined in the check in step 55 that a ≦ n · b does not hold, the state as it is (currently set state) is not preferable. A backlight adjustment signal for adjusting the brightness adjustment of the light 20 is generated and sent to the backlight control device 38. Therefore, the backlight control device 38 changes the brightness of the backlight 20 according to the received backlight adjustment signal, that is, darkens the backlight 20 (step 56), returns to step 53, and returns to the above-described step shown in FIG. Repeat the procedure.
[0026]
That is, the brightness of the backlight 20 changed to dark is detected by the backlight monitor 32 (step 53), the luminance a is again obtained by the leakage light luminance estimation unit 44 (step 54), and the backlight adjustment is performed in step 55. The signal generation unit 42 compares the luminance a obtained by the leakage light luminance estimation unit 44 with the luminance b previously obtained by the external light reflection luminance estimation unit 40 (checks whether a ≦ n · b is satisfied). ).
[0027]
Here, if it is determined in the check in step 55 that a ≦ n · b is established, this state (set state) may be maintained. If a ≦ n · b is not satisfied, the backlight 20 is further dimmed and steps 56 and 53 to 55 are repeated until a ≦ n · b is satisfied.
[0028]
According to the above embodiment, the brightness of the backlight 20 of the image display device can be controlled within a predetermined range with respect to external light (environment light) of the environment. For this reason, the display image can be easily observed.
[0029]
In the above embodiment, the brightness of the leakage light of the liquid crystal screen determined by the extinction ratio of the liquid crystal from the brightness of the backlight 20 of the liquid crystal panel unit 10 detected by the backlight monitor 32, that is, from the brightness value of the backlight 20. Although an example in which a relational expression, a table, etc., which are determined in advance are used when a is obtained, the present invention is not limited to this method.
[0030]
For example, as shown in FIG. 4A, a graph showing the relationship between the (cumulative) usage time of the backlight and the light emission luminance obtained in advance, and the backlight control as shown in FIG. Based on the content of the graph indicating the relationship between the signal and the emission luminance, the current backlight brightness is estimated, and this (estimated backlight brightness) and a predetermined backlight brightness value are calculated. And the above-mentioned luminance a may be estimated from the relationship between the leakage light determined by the extinction ratio of the liquid crystal.
[0031]
In this case, in the image display device 30 shown in FIGS. 1 and 2, instead of providing the backlight monitor 32, the light shown in FIG. 4A and FIG. It is stored in the memory 45 of the luminance estimation unit 44. Then, the leakage light luminance estimation unit 44 receives the (cumulative) usage time and / or backlight control signal of the backlight 20 from the backlight control device 38 or the backlight 20, and necessary graph relational expressions from the memory 45. Alternatively, the current brightness (light emission luminance value) of the backlight 20 may be obtained by reading a table.
At this time, the leakage light luminance estimation unit 44 uses the current brightness (emission luminance value) of the backlight 20 thus obtained instead of the detected monitor value (brightness) of the backlight monitor 32, and this backlight 20. From the light emission luminance value , the leakage light luminance (minimum liquid crystal luminance) a of the liquid crystal screen determined by the extinction ratio of the liquid crystal is calculated.
[0032]
In the above embodiment, when the brightness b due to the reflection of the liquid crystal screen corresponding to the ambient light state is obtained from the brightness of the external light detected by the external light monitor 34, a predetermined relational expression, table However, the present invention is not limited to this method.
For example, similarly, the brightness b due to the reflection of the liquid crystal screen corresponding to the brightness of the ambient light determined in advance is obtained from the brightness of the backlight 20 estimated above and the detection result of the brightness detection means of the ambient light. This is also an effective method.
[0033]
In the above-described various embodiments, a ≦ n · b (where n is 2 to 2) between the luminance a of the leakage light of the liquid crystal screen and the luminance b of the reflection of the liquid crystal screen corresponding to the brightness of the ambient light. When it is determined that 1) is established, the brightness of the backlight 20 is not adjusted, and the backlight 20 is maintained as it is (set state). However, the brightness of the backlight 20 is preferably as bright as possible, so that the brightness of the backlight 20 is 70% or more of the maximum brightness of the backlight 20 within a range where a ≦ n · b holds. Adjustment may be performed by the controller 36 or the backlight control device 38.
[0034]
It should be noted that each of the above embodiments shows an example of the present invention, and the present invention should not be limited to these.
[0035]
【The invention's effect】
As described above in detail, according to the present invention, in an image display device using a liquid crystal display device, it is possible to make a display image truly legible regardless of the brightness of ambient light (ambient light). It is possible to achieve a remarkable effect that an image display device can be realized.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a schematic configuration of an image display apparatus according to an embodiment of the present invention.
2 is a block diagram showing a schematic configuration of an embodiment of a control system of the image display apparatus shown in FIG. 1;
3 is a flowchart for explaining an operation corresponding to the brightness of the ambient light of the control system of the image display apparatus shown in FIG. 1;
FIG. 4A is a graph showing a relationship between a backlight usage time and light emission luminance obtained in advance, and FIG. 4B is a graph showing a relationship between a backlight control signal and light emission luminance.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Liquid crystal display panel part 12 Liquid crystal display panel 20 Backlight part 30 Image display apparatus 32 Backlight monitor 34 External light monitor 36 Controller 38 Backlight control apparatus 40 External light reflection luminance estimation part 41, 45 Memory 42 Backlight adjustment signal generation part 44 Leakage Light Intensity Estimator 51-56 Processing Step

Claims (4)

An image display device using a liquid crystal display device including a liquid crystal display panel and a backlight,
When the ambient light is bright , the backlight of the liquid crystal display device is brightened. When the ambient light is dark , the backlight is darkened so that the leakage light of the liquid crystal screen determined by the extinction ratio of the liquid crystal does not exceed a certain level. have a brightness adjustment means of the backlight,
The backlight brightness adjustment means includes:
First detection means for detecting the brightness of the backlight, and first luminance estimation means for estimating the luminance a of the leakage light based on an output signal from the first detection means;
A second detection means for detecting the brightness of the ambient light, and a brightness obtained by reflecting the brightness of the ambient light and the corresponding liquid crystal screen based on the output signal from the second detection means; second luminance estimating means for estimating the luminance b based on the relationship with b;
A backlight brightness adjustment signal generating means for controlling the brightness of the backlight based on outputs from the first brightness estimating means and the second brightness estimating means,
An image display device characterized in that the brightness of the backlight is controlled so that the luminance a is not more than twice the luminance b . The backlight brightness adjustment means includes:
Advance and the luminance value of the backlight which is determined, based on the relationship between the leakage light is determined by the extinction ratio of the liquid crystal, the relationship and the control of the backlight of the usage time of the backlight, which is determined in advance and the light-emitting luminance Means for estimating the luminance a of the leakage light of the liquid crystal screen from the brightness of the current backlight estimated based on the relationship between the signal and the emission luminance;
From the brightness of the ambient light detected by the means for detecting the brightness of the ambient light, based on the relationship between the brightness of the ambient light that is obtained in advance and the brightness b by reflection of the liquid crystal screen corresponding thereto, Means for obtaining luminance b due to reflection of the liquid crystal screen corresponding to the brightness of the ambient light,
The image display device according to claim 1 , wherein the brightness of the backlight is controlled so that the luminance a is not more than twice the luminance b. The backlight brightness adjustment means includes:
The brightness of the backlight is adjusted to be 70% or more of the maximum brightness of the backlight within a range where the brightness a is less than or equal to twice the brightness b. Image display device. The backlight brightness adjustment means includes:
The image display device according to claim 1, wherein the brightness a is adjusted to be equal to or less than the brightness b.

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